Two-fuel carburetor



Sept. 23, 1952 1.. D. BOYCE TWO-FUEL CARBURETOR Filed Feb. 12, 1949 @w w i ///////VV/ J INVENTOR. LEONARD D. BOYCE ATTORNFY Patented Sept. 23, 1952 TWO FUEL CARBURETOR Leonard D. Boyce, Kirkwood, Mo assignor to Carter Carburetor Corporation, St. Louis, Mo., a corporation of Delaware Application February 12, 1949, Serial No. 78,667

(Cl. 261 B) 4 Claims. 1

This invention relates to fuel supply devices for internal combustion engines and consists particularly in novel means for improving the efficiency of the engine by supplying fuels of different antiknock qualities, according to the power demand on the engine.

It is well known that when the carburetor throttle valve is opened and/or the speed of the engine is reduced upon increasing of the power demand on the engine, the compression in the engine cylinders increases so that ordinary fuels may be caused to detonate. In order to permit engines to operate at higher compressions with the consequent increased efficiencies, it is necessary to supply more expensive fuels having higher anti-knock qualities. However, during normal cruising of a vehicle in the so-called economy range, relative low compressions exist in the firing chambers and less expensive fuels of lower anti-knock ratings will serve just as well.

Accordingly, it is the main object of the present invention to provide an internal combustion engine with means for selectively supplying high and low anti-knock fuels according to the power demand on the engine.

A more detailed object is to provide means for alternately supplying high and low anti-knock fuels while insuring adequate fuel supply, particularly at the time of valve shifting.

These objects and other more detailed objects hereafter appearing are attained by the structure illustrated in the accompanying drawing in which Fig. 1 is a top view and horizontal section on line l-l of Fig. 2 and illustrating the carburetor portion of the intake system of an internal combustion engine embodying the invention.

Fig. 2 is a side view and vertical, central section of the same structure.

The carburetor illustrated is of the downdraft type including a mixture conduit 4 with a central Venturi tube portion 5, a jet bar 6, traversing the same, and a throttle valve 1 controlling the discharge of mixture from the lower end of the conduit. The throttle is manually controlled by means of a lever 8 secured to one end of the throttle shaft. A constant level bowl 9 is formed on one side of the mixture conduit and is centrally traversed by a vertical wall l forming a pair of fuel storage chambers II and I2. These chambers are connected to different fuel supply sources by means of fittings l3 and I4 and enclose floats I5 and I6 controlling the usual needle valves, one being shown at IT, for maintaining the fuel at substantially constant levels in both chambers.

Chamber II, which serves for storing fuel of relatively low anti-knock properties, has a metering orifice element IS in the lower portion thereof adjacent Wall Ii]. This element also serves for seating a ball valve l9 normally urged upwardly towards its seating position by a coiled spring 29. A calibrated metering plug 2| is threadedly secured in the lower portion of element :8. A valve actuator pin 22 is slidably received in a vertical orifice through the top of element 58 and serves to actuate valve ball 20 as will be described.

Fuel chamber l2, which serves for storing relatively high anti-knock fuel, has a metering orifice element 24 in the lower part thereof adjacent wall [0. Element 24 also forms a seat for a needle valve 25 which has a stem 26 paralleling pin 22. A plug 21 formed in the lower part of element 24, has a calibrated orifice somewhat larger than that in plug 2|.

Formed in wall l0, between metering orifice elements [8 and 24, is a vertical cylinder 30 in which works a piston 31 constantly urged upwardly by a coiled spring 32. Cylinder 30, beneath the piston, is connected by a passage 33 to the carburetor mixture conduit posterior to throttle valve 1. A yoke bar 34 secured to the top of piston 3!, has pin 22 secured to one end portion thereof and has a hole in the opposite end portion slidably receiving stem 26 on valve 25. A coiled spring 35 is compressed between yoke 34 and a collar or key 36 on stem 26.

A solenoid 4!! is mounted on top of bowl 9 and is connected through the normally open points of a switch 41 to the ignition circuit, the opposite side of the solenoid being conveniently grounded. A switch actuating plunger 42 depends into the interior of the solenoid and forms a portion of the core thereof. A short pin 43 on piston 3! projects oppositely into the solenoid.

A cross passage 46 extends beneath metering orifice elements l8 and 24 and communicates therewith and with an upwardly inclined main fuel passage 41 which opens laterally into, Venturi tube 5 through openings in the jet bar, as at 48. An air bleed tube 49 projects into the main fuel passage and communicates with the upper portion of the fuel bowl by means of cross passage 50 in the top of the jet bar. Idling fuel is supplied by means of an idling tube 5| communicating with the main fuel passage, and suitable passages, as at 52, formed in the wall of the mixture conduit and terminating in idle ports adjacent and posterior to the edge of the throttle valve when closed, in the usual manner. An accelerating pump, generally indicated at 55,

communicates with high anti-knock fuel chamber I2 through an inlet passage 56 and discharges into the mixture conduit through a pump nozzle When the engine is operating with the throttle closed or only partly open, that is in what is well known in the industry as the economy range, relatively high suctionexists in the mixture conduit posterior to the throttle and in cylinder 39 which draws piston 3i downwardly so as to open ball valve 19 by means of pin 22 and close needle valve 25 by means of coiled spring and stem 25. Fuel from low anti-knock chamber I I will be supplied under such conditions through the main nozzle passage ll or, during idling, through tube 5| and the idling ports. The lost motion connection between valve operating yoke 35 and stem" 23 insures full opening of ball valve i9 and proper seating of the needle valve without the danger of straining the parts. In casethe power demand on the engine should. increase, accompanied by opening of the throttle valve and/or. substantial lowering of the suction posterior to thethrottle valve and in cylinder 3&3, piston 35 will be moved upwardly by spring 32.; Just beiore ball valve. l9 starts to restrict metering orificeelement i8 and needlevalve' 25 starts to open, pinfi3; on piston 3! will engage switch actuator. plunger 52 closing switch 61 and energizing; the solenoid. There-.

upon, piston 38 and valve pin 22- and'stem 23 will be drawn rapidly upwardly to cause immediate seating ofball valveis and full opening of needle valve 25. This snap action insures rapidtransfer from low anti-knock. to high anti-knock fuel-so that full engine fuel requirements will be supplied at all'tiines.

.It should be noted that valves is and 25 are not metering valves themselves, but the larger size'oi' orifice plug 2? serves to suppl an enriched power mixture when the engine is operatinginthe power range, as wellas supplying fuel of superior anti-knock properties. =Sinal1er jet plug it provides a leaner mixture, when the engine isoper oting in the part throttlecr economy range. Accelerating pump 55 injects a pick upcharge of high anti-knock fuel during the transfer from economy to power range operation, the pump being operated. in this" instance; from the throttle valve by means of suitable linkage; but it may be operated by suction, as is wellknown.

The invention may modifiedin various respects as will occur to those skilled in the.- art and the exclusiveuse oiall modifications as conic within the scopeof the appended claims is contemplated.

I claim:

l. in a carburetor for-an:internalcombusfion engine, an intake conduit, a mainiuelzsupplypassage and a step-up fuel supply passage leading thereinto, a valve controlling .eachiof said: passages, and means moving saidvalves in a direction to open. and close the passages. respectively, said means including an actuator, a solenoid adjacent' said actuator, the solenoid arinatureibeing operatively connected tosaid actuator, a source of electric energy having a connecting circuit to said solenoid, a control switch in said circuit, and an operative connection between said means and said switch for closing said sw-itch to energize said solenoid,responsive to movement of said means in one direction.

2. In combination with an internal combustion engine, a fuel mixture conduit, a pair of fuel chambers adapted, respectively, for storing high and low octane fuels, an auxiliary and a main fuel supply passage leading, respectively, from said chambers to said conduit, a metering orifice in each supply passage, a valve controlling each of said orifices, and means moving said valve in a direction to open and close the orifices, respectively, said means including an actuator, a solenoid adjacent said actuator, the solenoid armature being operatively connected to said actuator, a source of electric energy having a, connecting circuit to said solenoid, a control switch in said circuit, and an operative connection between said means and said switch for closing said switch to energize said solenoid, responsive to movement or" said means in one direction.

3. In combination with an internal combustion engine, an intake conduit, a pair of fuel chambers for storing,re'spectively, high. anti-knock and low anti-knock. fuels, a main fuel supply passage leading from. saidlow anti-knock, chambena stepeup' passage from said high antiiznocl; chamber and of larger eiiectivecapacity than said main passage for supplying anenriched power mixture, an idling passage leading from main passage, metering orifices and control valves therefor in said main and step-up passages, and means movin said valves in a directionto open. and close the main and step-up passages, respectively, said means including an actuator, a solenoid. adjacent said actuator, the solenoid armature beingoperatively connected to said actuator, a source of electric energy having a connecting circuit to said solenoid, a control switch in said circuit, and anoperative connection bS'JWGEll said rieansand said switch for clos ing said switch to energize-said solenoid, responsive to. movement of said means in-one direction.

, 4 in a carburetorfor an internal combustion engine, an intake conduit, a main fuel supply passage and; a step-up fuel supply passage leading thereinto, a valve controlling each of said passages, and means-for sequentially moving said valves a direction to open and close said passages, respectively, said means including a sensin device movable responsive to pressure conditions insaid conduit, an actuator forsaid. valves, amotor connected to said actuator, a source of power for said motor having a connection to said motor, a control for the motor in said connection, and'an operative connection between said sensing device and said motor control for connecting said source and said motor to move said valve actuator responsive to movement of said sensing means-in one direction.

LEONARD Di BOYSE.

QE'IJED caring: references arev of record in the UNITED STrKTES PATENTS a 'Dec, 28, 1-943 

